Coordinated optical and radar measurements of low velocity meteors

摘要: Abstract To better estimate which luminous efficiency ( τ ) value is compatible with contemporary values of the ionization coefficient β ), we report a series simultaneous optical and specular echo radar measurements low speed (v i 20 km/s) meteors. We focus on population as secondary not relevant initial trail radii are small, minimizing model assumptions required to electron line density. By using large decrease in expected at such speeds, attempt define likely ratio photon production. This provides an probable efficiency, given that recent lab agree established theory (Jones, 1997; DeLuca et al., 2018) suggesting more constrained than . Optical were performed two pairs autonomously operated electron-multiplied charge coupled device cameras (EMCCDs) co-located multi-frequency Canadian Meteor Orbit Radar (CMOR) (Brown 2008). Using timing geometry individual meteors measured by both multi-station EMCCD systems, portion lightcurve corresponding each received power used A total 1249 identified from observations between 2017 – 2019 55 having atmosphere speeds below km/s. subset 36 events analyzed detail, 29 These had G-band magnitudes point +4 +7.7, average radiant 5W (assuming 945 W for zero magnitude meteor). correspond typical +6. Following procedure Weryk Brown (2013), density (q) (I) direct event. find / strongly correlates power. All our asteroidal-like orbits six found be iron meteoroids, representing 20% slow km/s sample. Luminous averaged 0.6% speed, ranging 0.1% almost 30%. No trend was apparent, though weak correlation higher may present.